1. Field of Invention
The present invention is related to a laser radar for a vehicle. More particularly, preferred laser radars comprise using a cylindrical reflector. In particular aspects, a laser radar for a vehicle is provided comprising using a cylindrical reflector, wherein a cylindrical reflector provided with a structure having a plurality of reflection mirrors preferably with reflection accuracy of 0.5° unit attached on an internal surface of the caliber thereof is used, hence allowing the laser scanning operation of the radar for a vehicle to be more stably accomplished and long and short distance detections to be accomplished.
2. Background
As the demand for more luxurious vehicle increases, a radar capable of detecting a distance from a vehicle ahead and its speed has been attached to a front side (bumper, grille, etc.) of the vehicle's body.
The radar for a vehicle is for the purpose of controlling a cruise and has been used in a traveling speed adaptation control, in which a distance from a vehicle ahead and its speed are detected to automatically trigger off braking or alarming in close proximity. The conventional radar and the operating method thereof will be briefly described below with reference to FIGS. 8 and 9.
The radar shown in FIG. 8 is the industrial radar and includes a laser diode (100) and a prism (200) which is rotatable by 0.5°, as the main components, and its laser scanning method includes the steps of: generating a laser beam from the laser diode (100); transmitting the laser beam to the object to be detected while reflecting the laser beam through the prism (200); receiving a laser beam reflected from the object to be detected; measuring the time difference between the transmitted laser beam and the received laser beam; and calculating the distance from the object to be detected using the time difference.
However, there is a disadvantage in that, since the conventional radar shown in FIG. 8 uses a prism, performance can be compromised as a result of vibration of the vehicle body in traveling so that precise transmission of a laser beam is not accomplished. Moreover since the prism rotates, an additional designing is required to reduce the rotation momentum. Furthermore, since a more mechanical driver for the prism is required, it is difficult to manufacture radar itself in small size.
The radar shown in FIG. 9 is radar for a vehicle and includes a lens module (500) having a transmitter (300) with a laser diode (100) and a receiver (400) for receiving a laser beam, as the main components, and its laser scanning method includes the steps of: generating a laser beam from the laser diode (100) installed in the transmitter (300); radiating the laser beam through a lens of the lens module (500) to transmit it to the object to be detected; receiving the laser beam reflected from the object to be detected; measuring the time difference between the transmitted laser beam and the received laser beam; and horizontally moving the lens module (500) to measure the size of the object to be detected.
However, the disadvantage for the conventional radar shown in FIG. 9 is that it cannot detect an object at various angles using a laser, while a laser beam detection angle is very narrow at about 4 to 6°. It also has the disadvantage of the need to further install laser distance detection devices for long and short distance detections, separately, in order to perform short or long distance detection.
As the conventional radar device for a vehicle, in Korean Patent Publication No. 1999-022667 has been disclosed an optical radar device including: a light emitting means; a horizontal scanning means having a spiral form in which the apex angle of a prism is continuously changed to scan light emitting from the light emitting means; an actuator for rotating the horizontal scanning means; and a light receiving means for receiving light reflected from an object. However, the disadvantage of the aforementioned radar device for a vehicle is the imprecise laser transmission due to the application of prism that is weak to the vibration of the vehicle body.
In Japanese Patent Laid-open Publication No. Hei 8-261753 (11 Oct., 1996) has been disclosed an optical radar device for controlling a laser beam emitted from a light emitting device at an arbitrary angle through a polygonal mirror rotated by a motor with a disadvantage of narrow range for the laser transmission due to similar structure of the polygonal mirror to a prism.
In Japanese Patent Laid-open Publication No. Hei 8-248131 (27 Sep., 1996) has been disclosed a laser radar device including a radiation optical system provided with a laser beam source for emitting a laser beam, a rotation mirror for reflecting the laser beam in a scanning direction while rotating at a constant velocity, in order to change a radiation angle of the laser beam nonlinearly with respect to time. Yet, it has a disadvantage of narrow range for the laser transmission and a detection range for an object, although a radiation angle can be changed using a rotating mirror.
In Japanese Patent Laid-open Publication No. Hei 7-140248 (2 Jun., 1996) has been disclosed a laser radar device wherein a laser beam radiated from a laser beam source is rotated by a motor; radiated onto an object while passing through a mirror formed in a multi reflection type in which its top and bottom are inclined in a beam source direction; and then received to measure the distance from the object. Yet, it still has a disadvantage of narrow range for the laser transmission and a detection range for an object, although a radiation angle can be changed using a rotating mirror.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.